Various electrodes which are adhered and secured to the skin surface of a patient have been developed as a biomedical electrode to a cardiomotile electric current and potential. In such electrodes, an electrically conductive cream or paste is interposed between the electrode and the skin surface of the living body to improve electrical contact.
On the other hand, a substantially circular disposable biomedical electrode has been developed from the standpoint of the convenience of its application to the skin. This biomedical electrode comprises an electrically conductive electrode plate of metal foil having provided on one side thereof an electrically conductive adhesive layer. This conventional disposable biomedical electrode is designed to have a tab on the edges of the electrically conductive plate so as to connect it to a biomedical diagnostic apparatus. This conventional biomedical electrode is advantageous in its attachment to a body and handling, and also unnecessity of cleaning up the skin surface as compared with use of the electrically conductive cream or paste.
The use of the electrically conductive cream or paste involves various disadvantages in complication of its application, poor adhesion to the skin when sweated, and contamination of the skin surface.
Further, the conventional biomedical electrode is arranged to have the tab on the edges of the electrically conductive electrode plate, so that when a lead wire terminal such as a clip or the like which connects to the biomedical diagnostic apparatus is coupled to the tab, stress is exerted. Such stress is also applied to the marginal edge of the electrically conductive adhesive layer to lift the biomedical electrode by means of the terminal, thereby involving cleavage stress between the skin surface and the adhesive layer after connection. For this reason, the conductive adhesive layer is lifted beyond the tab or peeled therefrom to result in lack of stability of electric signal due to poor adhesion. This is also the prominent phenomenon when the biomedical electrode is used in monitoring for a long period of time.
The electrically conductive electrode plate comprises silver/silver chloride, nickel, tin, chromium or the like, which is a non-polarizable material and an expensive material. Considering reduction in production cost which is an important factor as a ready and disposable biomedical electrode, a formation of the tab which extends beyond the edges of the electrode plate is not considered to be satisfactory from the standpoints of complication of production step and the decrease of yield.